System and method for determining inductance of a power cable

ABSTRACT

A welding system monitors the changes in the power output provided from a power supply to a device to determine the inductance of power cables between the power supply and the device. The device may determine the inductance of the power cables based at least in part on a delay in a threshold change in voltage to the device after a change in the current demand of the device, a delay in the initialization of the change in the current demand of the device after an initialization signal, a rate of change of the current drawn by the device, or a relative comparison of the voltage to the device and the current drawn by the device, or any combination thereof. If the inductance of the power cables is greater than a threshold inductance, the device may signal the user, disable operation of the device, or any combination thereof.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.14/616,333, filed Feb. 6, 2015, entitled “SYSTEM AND METHOD FORDETERMINING INDUCTANCE OF A POWER CABLE,” which claims priority from andthe benefit of U.S. Provisional Application Ser. No. 61/976,284,entitled “SYSTEM AND METHOD FOR DETERMINING INDUCTANCE OF POWER CABLE,”filed Apr. 7, 2014, the entireties of which applications are herebyincorporated by reference in their entirety for all purposes.

BACKGROUND

The invention relates generally to welding systems, and, moreparticularly, to determining an inductance of one or more power cables,such as power cables between a power supply and a welding device.

Welding systems support a variety of processes, such as metal inert gas(MIG) welding, tungsten inert gas (TIG) welding, stick welding, and soforth, which may operate in different modes, such as constant current orconstant voltage. Certain welding applications, such as boiler servicingand repair, shipyard work, construction, and so forth, may position awelding location or workpiece large distances from a welding powersource.

Power cables supply output power to a welding application from thewelding power source. Advanced forms of MIG welding are based upongeneration of pulsed power to deposit welding wire on the workpiece.However, power cables can be arranged between a welding power source anda welding application such that an inductance of the power cables mayaffect the timing or amplitude of the welding application.

BRIEF DESCRIPTION

Certain embodiments commensurate in scope with the originally claimedinvention are summarized below. These embodiments are not intended tolimit the scope of the claimed invention, but rather these embodimentsare intended only to provide a brief summary of possible forms of theinvention. Indeed, the invention may encompass a variety of forms thatmay be similar to or different from the embodiments set forth below.

In one embodiment, a welding system monitors the changes in the poweroutput provided from a power supply to a device to determine theinductance of power cables between the power supply and the device. Thedevice may determine the inductance of the power cables based at leastin part on a delay in a threshold change in voltage to the device aftera change in the current demand of the device, a delay in theinitialization of the change in the current demand of the device afteran initialization signal, a rate of change of the current drawn by thedevice, or a relative comparison of the voltage to the device and thecurrent drawn by the device, or any combination thereof. If theinductance of the power cables is greater than a threshold inductance,the device may signal the user. The device may disable operation withthe power supply while the inductance of the power cables is greaterthan the threshold inductance. The user may adjust the arrangement ofthe power cables and/or replace the power cables to affect theinductance of the power cables. When the inductance of the power cablesis less than the threshold inductance, the device may enable operationwith the power supply. During idle operation of the welding system, thedevice may determine the inductance of the power cables at varioustimes. For example, the device may determine the inductance of the powercables at start up of the welding system, periodically during operationof the welding system, and/or at random intervals during operation ofthe welding system.

DRAWINGS

These and other features, aspects, and advantages of the presentinvention will become better understood when the following detaileddescription is read with reference to the accompanying drawings in whichlike characters represent like parts throughout the drawings, wherein:

FIG. 1 is a block diagram of a welding system having a welding powersource and an advanced process wire feeder in accordance with aspects ofthe present disclosure;

FIG. 2 is a block diagram of an embodiment of the advanced process wirefeeder of FIG. 1;

FIG. 3 is a front perspective view of an advanced process wire feeder inaccordance with aspects of the present disclosure;

FIG. 4 is a top view of an embodiment of the advanced process wirefeeder of FIG. 3;

FIG. 5 is a block diagram of an embodiment of the advanced process wirefeeder employing power conversion circuitry, relay circuitry, sensingcircuitry, and a wire feed assembly in accordance with aspects of thepresent disclosure;

FIG. 6 is a schematic diagram of an embodiment of the relay circuitry ofFIG. 5;

FIG. 7 is a flow chart of an embodiment of a process for producingcontrolled waveform output using an advanced process wire feeder;

FIG. 8 is a flow chart of an embodiment of a process for sensingpolarity of input power supplied to an advanced process wire feeder;

FIG. 9A is a first part of a flow chart of an embodiment of a processfor actuating relay circuitry of an advanced process wire feeder;

FIG. 9B is a second part of the flow chart of FIG. 9A of the process foractuating relay circuitry of the advanced process feeder;

FIG. 10 is a flow chart of an embodiment of a process for adjustingpower conversion circuitry of an advanced process wire feeder;

FIG. 11 is a chart of bus voltage, input current, output voltage, andoutput current versus time;

FIG. 12 is another chart of bus voltage, input current, output voltage,and output current versus time;

FIG. 13 is a diagram of an exemplary circuit for controlling applicationof power to a welding component such as a wire feeder or pendant duringpower-up or connection of the component to a welding power supply;

FIG. 14 is a somewhat more detailed diagram of an exemplary circuit forcontrolling inrush current to a welding pendant;

FIG. 15 is a similar detailed diagram of an exemplary circuit forcontrolling inrush current to a welding wire feeder;

FIG. 16 is an embodiment of a welding system with power cables to couplea device to a power supply;

FIG. 17 is a chart of input voltage and input current versus time, wherethe input voltage and input current are provided over power cables to adevice; and

FIG. 18 is a flow chart of an embodiment of a method for determining aninductance of power cables between a power supply and a device of thewelding system.

DETAILED DESCRIPTION

One or more specific embodiments of the present disclosure will bedescribed below. In an effort to provide a concise description of theseembodiments, all features of an actual implementation may not bedescribed in the specification. It should be appreciated that in thedevelopment of any such actual implementation, as in any engineering ordesign project, numerous implementation-specific decisions must be madeto achieve the developers' specific goals, such as compliance withsystem-related and business-related constraints, which may vary from oneimplementation to another. Moreover, it should be appreciated that sucha development effort might be complex and time consuming, but wouldnevertheless be a routine undertaking of design, fabrication, andmanufacture for those of ordinary skill having the benefit of thisdisclosure.

When introducing elements of various embodiments of the presentdisclosure, the articles “a,” “an,” “the,” and “said” are intended tomean that there are one or more of the elements. The terms “comprising,”“including,” and “having” are intended to be inclusive and mean thatthere may be additional elements other than the listed elements.

Welding systems include a power supply that provides a power output toone or more devices along power cables. The devices coupled to the powersupply may include, but are not limited to a wire feeder, an advancedprocess wire feeder, an induction heater, a plasma cutter, a powergenerator, or any combination thereof. The inductance of the powercables may delay the current input to the device, thereby affecting thetime that the power output provided from the power supply is availableto the device. As discussed in detail below, the device (e.g., advancedprocess wire feeder) may reduce or eliminate the effect that theinductance of the power cables has on the output of the device. Forexample, the device may utilize power storage circuitry (e.g., buscapacitor, battery) to enable the device to provide a desired output fora period of time when the output power from the device is different thanthe input power received from the power supply. FIGS. 1-15 belowdescribe embodiments of a welding system 10 with an advanced processwire feeder 20 coupled to a power supply 12 via power cables 24. Theadvanced process wire feeder 20 may reduce or eliminate the effect thatan inductance of the power cables 24 may have on the welding output of atorch 14 coupled to the welding system 10. FIGS. 16-18 below describeembodiments of a welding system 10 with a device 310 that may determinethe inductance of the power cables 24. The device 310 may compare theinductance of the power cables 24 to a threshold inductance, and mayprovide a signal to a user when the determined inductance is greaterthan the threshold inductance. The control circuitry of the device 310may disable operation of the device 310 while the determined inductanceof the power cables 24 is greater than the threshold inductance, therebyprotecting circuitry components of the device 310 and/or maintaining adesired quality of output from the device 310. As may be appreciated,the device 310 may include, but is not limited to, the advanced processwire feeder 20.

Although described herein as determining inductance of the power cables24 and implementing a change in the operation of the device 310 based onthe determined inductance, in other embodiments, some other parameterindicative of a delay in the welding system 10 may be determined and achange in the operation of the device 310 may be implemented based onthis other parameter. In other words, while the parameter indicative ofthe delay that is determined by the control circuitry of the device 310may, in some embodiments, be analogous to the inductance in the powercables 24, this parameter may only bear some relation to inductance inthe power cables 24 in other embodiments. For example, in certainembodiments, there may be a direct (e.g., 1:1 relationship) between thedetermined parameter indicative of the delay and the inductance of thepower cables 24 in some embodiments, whereas in other embodiments theinductance of the power cables 24 may only be one factor that affectsthe parameter indicative of the delay. In general, however, theparameter indicative of delay in the welding system 10 may be at leastpartially affected by the inductance in the power cables 24 or, atleast, in an inductance of the welding system 10 in general.

FIG. 1 is a block diagram of an embodiment of a welding system 10 whichpowers a welding application. As illustrated, the welding system 10includes a welding power source 12 and a coupled welding torch 14. Thewelding power source 12 supplies input power to the welding torch 14.The welding torch 14 may be a torch configured for stick welding,tungsten inert gas (TIG) welding, or gas metal arc welding (GMAW), basedon the desired welding application. In some embodiments, the weldingpower source 12 supplies input power to a pendant 16 coupled to a torch14 configured for stick welding or TIG welding. The operator suppliesthe filler metal, if any, for stick or TIG welding. The pendant 16 maybe configured to control the power source 12 and/or notify the operatorof welding parameters. In other embodiments, the welding power source 12supplies input power to a standard wire feeder 18. The standard wirefeeder 18 supplies the input power and filler metal to a welding torch14 configured for GMAW welding or flux core arc welding (FCAW). In someembodiments, the welding power source 12 supplies input power to anadvanced process wire feeder 20. The advanced process wire feeder 20 isconfigured to convert the input power of the welding power source 12 towelding output. In some embodiments, the welding output of the advancedprocess wire feeder 20 may be a controlled waveform welding output.Controlled waveform welding outputs include welding outputs adapted to apulsed welding process or a short circuit welding process.

The welding power source 12 is coupled to an alternating current (AC)source 22, such as an electrical grid or engine-driven generator thatsupplies primary power. The welding power source 12 may process theprimary power to input power supplied to the welding torch 14 via powercables 24. In some embodiments, the power cables 24 includes a firstterminal 26 and a second terminal 28, wherein one terminal has apositive polarity and the other has a negative polarity. Powerconversion circuitry 30 converts the AC current to input power as eitherdirect current (DC) or AC. The power conversion circuitry 30 may includecircuit elements such as transformers, switches, boost converters,inverters, and so forth, capable of converting power as dictated by thedemands of the welding system 12. In some embodiments, the powerconversion circuitry 30 is configured to convert the primary power to anapproximately 80V DC input power to supply the pendant 16, standard wirefeeder 18, or advanced process wire feeder 20. The input power may bebetween approximately 50 to 120V DC.

The welding power source 12 includes control circuitry 32 and anoperator interface 34. The control circuitry 32 controls the operationsof the welding power source 12 and may receive input from the operatorinterface 34 through which an operator may choose a welding process(e.g., stick, TIG, MIG) and input desired parameters of the input power(e.g., voltages, currents, particular pulsed or non-pulsed weldingregimes, and so forth). The control circuitry 32 may be configured toreceive and process a plurality of inputs regarding the performance anddemands of the system 12. The control circuitry 32 may include volatileor non-volatile memory, such as ROM, RAM, magnetic storage memory,optical storage memory, or a combination thereof. In addition, a varietyof control parameters may be stored in the memory along with codeconfigured to provide a specific output (e.g., reverse polarity,pre-charge capacitor, enable gas flow, etc.) during operation.

The welding power source 12 may include polarity reversing circuitry 36and communications circuitry 38 coupled to the control circuitry 32. Thepolarity reversing circuitry 36 reverses the polarity of the first andsecond terminals 26, 28 when directed by the control circuitry 32. Forexample, some welding processes, such as TIG welding, may enable adesired weld when the electrode has a negative polarity, known as DCelectrode negative (DCEN). Other welding processes, such as stick orGMAW welding, may enable a desired weld when the electrode has apositive polarity, known as DC electrode positive (DCEP). When switchingbetween a TIG welding process and a GMAW welding process, the polarityreversing circuitry 36 may be configured to reverse the polarity fromDCEN to DCEP. The operator may reverse the polarity manually, or thecontrol circuitry 32 may direct the polarity reversing circuitry 36 toreverse the polarity in response to signals received through thecommunications circuitry 38. The communications circuitry 38 isconfigured to communicate with the welding torch 14, pendant 16,standard wire feeder 18, advanced wire feeder 20, and/or other devicecoupled to the power cables 24. In some embodiments, the communicationscircuitry 38 is configured to send and receive command and/or feedbacksignals over the welding power cables 24 used to supply the input power.In other embodiments, the communications circuitry 38 is configured tocommunicate wirelessly with another device.

Devices including the pendant 16, standard wire feeder 18, and advancedprocess wire feeder 20 receive input power through the input terminal 40configured to couple with the first and second terminals 26, 28 of thepower cables 24. In some embodiments, the first terminal 26 isconfigured to connect with the input terminal 40 and the second terminal28 is configured to connect with the clamp 42 coupled to the workpiece44. In some embodiments, the input terminal 40 has input connectionswith defined polarities configured to couple to the respective first andsecond terminals 26, 28 of the same polarities, and the clamp 42 couplesto the pendant 16 or wire feeder 18. The advanced process wire feeder 20is configured to couple to the first and second terminals 26, 28 withinput terminals 40, and the clamp 42 is coupled to the advanced processwire feeder 20.

For some welding processes (e.g., TIG, GMAW), a shielding gas isutilized during welding. In some embodiments, as shown in the dashedlines, the welding power source 12 includes one or more gas controlvalves 46 configured to control a gas flow from a gas source 48. The gascontrol valves 46 may be controlled by the control circuitry 32. Thewelding power source 12 may be coupled to one or more gas sources 48because some welding processes may utilize different shielding gasesthan others. In some embodiments, the welding power source 12 isconfigured to supply the gas with the input power via a combined inputcable 50. In other embodiments, the gas control valves 46 and gas source48 may be separate from the welding power source 12. For example, thegas control valves 46 may be disposed within the standard or advancedwire feeder 18, 20. The standard and advanced wire feeders 18, 20 shownin FIG. 1 are coupled to GMAW torches 52 configured to supply the gasand welding wire 54 to the welding application.

FIG. 2 illustrates a block diagram an embodiment of the advanced processwire feeder 20 for converting input power to controlled waveform weldingoutput. The advanced process wire feeder 20 receives the input powerfrom the welding power source through input terminals 40 coupled toprocess circuitry 56. In some embodiments, the advanced process wirefeeder 20 is operated remotely from the welding power source with longpower cables. Process circuitry 56 may include circuitry such as relaycircuitry, voltage and current sensing circuitry, power storagecircuitry, and so forth, capable of sensing and controlling the inputpower received by the advanced process wire feeder 20. The processcircuitry 56 transmits the input power to the power conversion circuitry58.

Power conversion circuitry 58 is configured to convert the input powerfrom the welding power source to welding output suitable for performingwelding applications. Power conversion circuitry 58 may include circuitelements such as boost converters, buck converters, an internal bus, buscapacitor, voltage and current sensors, and so forth, capable ofconverting the input power to welding output. In some embodiments, inputpower received by the advanced process wire feeder 20 is a DC voltagebetween approximately 20V to 120V, approximately 40V to 100V, orapproximately 60V to 80V. As used in reference to the input power, theterm approximately may mean within 5 volts or within 10 percent of thedesired voltage. The power conversion circuitry 58 may be configured toconvert the input power to a controlled waveform welding output, such asa pulsed welding process or a short circuit welding process (e.g.,regulated metal deposition (RMD™)). The power conversion circuitry 58disposed within the advanced process wire feeder 20 supplies thecontrolled waveform welding output for the welding application withoutattenuation from the power cable between the welding power source andthe advanced process wire feeder 20. This increases the response timeand accuracy of the controlled waveform welding output supplied to thewelding torch. Increasing the response time of the controlled waveformwelding output may ensure that the desired welding output waveform issupplied to welding torch at specific times during the weld. Forexample, the RMD™ welding process utilizes a controlled waveform weldingoutput having a current waveform that varies at specific points in timeover a short circuit cycle. Increasing the response time of thecontrolled waveform welding output may also improve the timing of thewaveform pulses to produce a desired weld.

In some embodiments, the power conversion circuitry 58 is configured toprovide the welding output to the wire feed assembly 60. The wire feedassembly 60 supplies welding wire 54 to the welding torch for thewelding operation. The wire feed assembly 60 includes elements such as aspool, wire feed drive, drive rolls, and wire feed control circuitry.The wire feed assembly 60 feeds welding wire 54 to the welding torchalong a weld cable 62. The welding output may be supplied through theweld cable 62 coupled to the welding torch and/or the work cable 64coupled to the workpiece.

Presently contemplated embodiments of the advanced process wire feeder20 have a process operator interface 66 and a control operator interface68 for control of parameters of the welding system. The process operatorinterface 66 is coupled to the process circuitry 56 for operatorselection and adjustment of the welding process (e.g., pulsed,short-circuit, FCAW) through selection of the wire size, wire type,material, and gas parameters. The process operator interface 66 iscoupled to the wire feed assembly 60 for control of supplying thewelding wire 54 to the welding torch. The control operator interface 68is coupled to the process circuitry 56 to adjust the voltage, amperage,wire feed speed, and arc length for a welding application. In someembodiments, the process operator interface 66 and the control operatorinterface 68 are separate interfaces, each with respective controlcircuitry. Alternatively, the process operator interface 66 and thecontrol operator interface 68 may have common control circuitry and/orform a common control and process operator interface. The processoperator interface 66 and/or the control operator interface 68 mayinclude volatile or non-volatile memory, such as ROM, RAM, magneticstorage memory, optical storage memory, or a combination thereof. Inaddition, a variety of parameters may be stored in the memory along withcode configured to provide a specific output for default parametersduring operation.

The process interface 66 is configured to receive input such as wirematerial (e.g., steel, aluminum), wire type (e.g., solid, cored), wirediameter, gas type, and so forth. Upon receiving the input, the processcircuitry 56 is configured to determine the controlled waveform weldingoutput for the welding application. For example, the process circuitry56 determines the pulse width, relative pulse amplitude, and/or waveshape for a controlled waveform welding output process based at least inpart on the input received through the process interface 66. The wirefeed assembly 60 may be configured to supply the welding wire 54 basedon code or instructions stored in memory based on the received input.The wire feed assembly 60 is coupled to a process operator interface 66and control operator interface 68 for controlling the welding wire 54supplied for a welding operation. The wire feed assembly 60 adjustsparameters for supplying the welding wire 54 to the welding torch basedat least in part on operator input received via the process operatorinterface 66 or the operator interface 68. The control operatorinterface 68 is configured to receive operator input for parameters suchas the amperage, voltage, polarity, wire feed rate, arc length, processtype (e.g., RMD™, pulsed welding), and so forth. In some embodiments,the control operator interface is configured to adjust the power of thecontrolled waveform welding output without affecting the shape of thecontrolled waveform welding output. The process circuitry 56 adjusts thepower conversion circuitry 58 and wire feed assembly 60 based at leastin part on operator input received via the control operator interface68. In some embodiments, communications circuitry 70 coupled to theprocess circuitry 56 is configured to send and receive command and/orfeedback signals over the power cable used to provide the input power.The communications circuitry 70 enables the process operator interface66 and/or control operator 68 to control the welding power source. Forexample, the process operator interface 66 and/or control operator 68may be configured to control the amperage, voltage, or other parametersof the input power supplied by the welding power source. In someembodiments, the process circuitry 56 controls the welding power sourceremote from the welding power source without being restricted toparameters set on the operator interface 34 (FIG. 1). That is, theprocess circuitry 56 and communications circuitry 70 enables an operatorto control the welding power source remotely through the advancedprocess wire feeder 20 with equal control priority to the operatorinterface 34 of the welding power source.

Some embodiments of the advanced process wire feeder 20 include a valveassembly 72 for providing gas to the welding torch along a gas line 74.The valve assembly 72 may be controlled by the process circuitry 56and/or the wire feed assembly 60 as shown by the dashed control lines.For example, the valve assembly 72 may be configured to supply gas tothe welding torch prior to and after a welding application. In someembodiments, the valve assembly 72 is configured to purge the gas line74 upon receiving a purge command from the process operator interface 66or the control operator interface 68.

FIG. 3 illustrates a front perspective view of an embodiment of theadvanced process wire feeder 20 disposed in an enclosure 76 having theprocess operator interface 66 separate from the control operatorinterface 68. In some embodiments, the advanced process wire feeder 20is disposed in an enclosure 76 having an enclosure base 78 and enclosurecover 80 to shield the wire feed assembly 60 from the operatingenvironment when the enclosure 76 is closed. The enclosure 76 may besubstantially portable (e.g., suitcase feeder) and configured for manualoperator transport to a welding application remote from the weldingpower source. The enclosure cover 80 is shown in dashed lines forclarity to illustrate an embodiment of the wire feed assembly 60disposed within the enclosure.

The control operator interface 68 may be disposed outside the enclosure76 as illustrated in FIG. 3. The control operator interface 68 mayinclude one or more dials 82, one or more displays 84, and one or morebuttons 86. In some embodiments, the dials 82 may be configured toadjust voltage and/or amperage of the input power or welding output,wire speed, or arc length, or combinations thereof. One or more buttons86 may enable the operator to select process types, operatorpreferences, or process parameters previously stored in memory, orcombinations thereof. The control operator interface 68 may enableoperator selection of process parameters stored in memory, such aspreviously selected amperage and wire speed for the selected controlledwaveform welding process. The displays 84 may be configured to displayadjusted process parameters and/or selected process type (e.g., RMD™,pulsed welding, FCAW, MIG). In some embodiments, the one or moredisplays 84, lights, or other devices may be configured to provide anoperator-perceptible notification to notify the operator if thepolarities of the coupled power cables correspond to the respectiveinput terminals 40.

Embodiments of the advanced process wire feeder 20 include one or morespools 88 of welding wire 54 disposed within the enclosure 76 to supplythe wire feed drive 90. The welding wire 54 is pulled through the wirefeed drive 90 and an output terminal 91 to the weld cable 62. In someembodiments, the gas line 74 may be within the weld cable 62 asillustrated. A work cable 64 is coupled to the output terminal 91.

FIG. 4 illustrates a top view of an embodiment of the advanced processwire feeder 20 with the process operator interface 66 disposed withinthe enclosure 76. The process operator interface 66 may include one ormore buttons 92 and one or more indicators 94 to receive and displaywire and material parameters. In some embodiments, the process operatorinterface 66 may be configured to receive gas parameters. The one ormore buttons 92 of the process operator interface 66 may be configuredto receive input such as wire material (e.g., steel, aluminum), wiretype (e.g., solid, cored), wire diameter, and gas type. In someembodiments, the wire and/or gas parameters may be adjusted lessfrequently than the control parameters selected through the controloperator interface 68. For example, process operator interface 66 may bedisposed within the enclosure that is normally closed during welding. Asanother example, the process operator interface 66 may be adjustedprimarily when changing the spool 88 of welding wire 54. Indicators 94may include displays, lights, or other devices configured to provide anoperator-perceptible notification indicating the selected wire and/orgas parameters. Two or more drive wheels 98 of the wire feed drive 90are configured to direct the welding wire 54 through the output terminal91 along the weld cable 62.

FIG. 5 illustrates a block diagram of an embodiment of the advancedprocess wire feeder 20 having process circuitry 56, power conversioncircuitry 58, and a wire feed assembly 60. Embodiments of the advancedprocess wire feeder 20 may be coupled to long power cables 24 having aninductance 100. As may be appreciated, the power cables 24 may beconventional power cables 24. As discussed above, the advanced processwire feeder 20 may be located remotely from the welding power source.For example, the advanced process wire feeder 20 may be disposed betweenapproximately 30 to 200 feet, approximately 50 to 150 feet, orapproximately 100 to 150 feet from the welding power source 12. In someembodiments, the remotely located advanced process wire feeder may be ina different building, structure, or room than the welding power source12. The inductance 100 may vary during use as the power cables 24 arecoiled, extended, and moved.

The power conversion circuitry 58 is configured to receive the inputpower from the power cables 24 and convert the input power to weldingoutput. The power conversion circuitry may convert the input power towelding output without regard to the inductance 100 of the power cables24. Process control circuitry 102 controls the power conversioncircuitry 58 based at least in part on parameters received from theprocess operator interface 66 and/or control operator interface 68. Theprocess control circuitry 102 controls a boost converter 104 and a buckconverter 106 to convert the input power to welding output. An internalbus 108 may be disposed between the boost converter 104 and buckconverter 106. Only one boost converter 104 and buck converter 106 arediscussed herein for clarity, however, other embodiments of the powerconversion circuitry 58 may have one or more boost converters 104 and/orone or more buck converters 106. The boost converter 104 and buckconverter 106 are configured to convert the input power to weldingoutput suitable for controlled waveform welding processes, such as forRMD™ and pulse welding processes.

The boost converter 104 receives DC voltage from the input terminals 40and steps-up, or increases, the DC voltage of the bus power supplied tothe buck converter 106. As may be appreciated, the boost converter 104converts the DC input power from the welding power source to asubstantially pulsed stepped-up voltage DC bus power using a switch(e.g., FET) to open and close a boost circuit. The stepped-up voltage ofthe DC bus power is based at least upon the duty cycle of the switch.Varying the duty cycle of the switch affects the timing of when thestepped-up voltage DC bus power is supplied to the internal bus 108. Bycontrolling the switch of the boost converter 104, the process controlcircuitry 102 may adjust the timing, voltage, and amperage of the DC buspower.

The buck converter 106 receives the stepped-up voltage DC bus power andsteps-down, or decreases, the DC voltage to control the amperage of thewelding output. As may be appreciated, the buck converter 106 convertsthe pulsed, stepped-up voltage DC bus power to a pulsed, stepped-downvoltage DC welding output using a switch (e.g., FET) to open and close abuck circuit. As with the boost converter 104, varying the duty cycle ofthe switch of the buck converter 106 affects the timing of when thestepped-down voltage DC welding output is supplied to the welding torch.In some embodiments, multiple buck converters 106 may be coupled to theinternal bus 108 in parallel and controlled separately to affect thetiming and amplitude of changes (e.g., pulses) to the welding output. Bycontrolling the switch of the buck converter 106, the process controlcircuitry 102 may adjust the timing, voltage, and amperage of the DCwelding output. The control circuitry 102 is configured to control theswitches of the boost and buck converters 104, 106 to dynamically adjustthe voltage and/or amperage of the DC welding output supplied to thetorch based on the operator selected welding process (e.g., RMD™, pulsedwelding, FCAW, MIG). In some embodiments, the process control circuitry102 is configured to control the boost converter 104 and/or buckconverter 106 based on sensed parameters of the input power, bus power,or welding output, or combinations thereof. For example, the controlcircuitry 102 may control the boost converter 104 based on sensedparameters of the welding output to control the voltage across theinternal bus 108.

In some embodiments, a power storage circuit (e.g., bus capacitor 110)may be disposed on the internal bus 108. The bus capacitor 110 maypartially protect the boost converter 104 and/or buck converter 106 froma difference between the input power into the power conversion circuitry58 and the welding output from the power conversion circuitry 58 at anytime. As discussed above, the bus power converted by the boost converter104 is directed to the internal bus 108, then the buck converter 106.The bus capacitor 110 may be configured to store the bus power until itis received by the buck converter 106. Storing and dischargingrelatively large amounts of power in the bus capacitor 110 may heat thebus capacitor. The voltage difference between the bus power supplied bythe boost converter 104 and the bus power removed by the buck converter106 to convert to welding output may be measured as voltage ripple.Decreasing the magnitude of the voltage ripple may improve the weldquality and/or maintain the temperature of the bus capacitor 110. Thesize and capacitance of the bus capacitor 110 may be based on themagnitude of the voltage ripple, which is affected at least in part oncontrol of the boost converter 104 and the buck converter 106. The buscapacitor 110 may partially attenuate and/or delay the voltage ripple.

In some embodiments, the process control circuitry 102 is configured tocontrol the duty cycles of the boost converter 104 and the buckconverter 106 to reduce the voltage ripple of the bus capacitor 110based at least in part on sensed parameters of the input power andwelding output. The current and voltage of the input power are sensed atthe first and second connections 112, 114 by sensing circuitry 116through input sensors 118. The sensing circuitry 116 senses the currentand voltage at the internal bus 108 across the bus capacitor 110 throughbus sensors 120, and senses the current and voltage of the weldingoutput through output sensors 122. The process control circuitry 102 maydrive the boost converter 104 and the buck converter 106 based at leastin part on sensed parameters (e.g., voltage, current) of the weldingoutput, the input power, or the bus power, or combinations thereof. Forexample, the sensing circuitry 116 may sense the voltage and current ofthe welding output with welding output sensors 122 and sense the voltageof the input power and bus power with input sensors 118 and bus sensors120. In some embodiments, the process control circuitry 102 isconfigured to determine the product (i.e., power) of the welding outputcurrent and voltage and loss of the power conversion circuitry 58, todetermine the sum of the loss and the product, to divide the sum by theinput voltage to determine the desired bus current, and to drive theboost converter 104 to control the bus current. The boost converter 104may control the bus current to the desired bus current to substantiallymatch the bus power into the internal bus 108 with the welding outputremoved from the internal bus 108. The inductance 100 of the powercables 24 delays the current flow into the internal bus 108 from thewelding power source. Controlling the boost converter 104 based on theinput sensors 118 and/or bus sensors 120 rather than the current andvoltage of the input power at the welding power source reduces thevoltage ripple on the bus capacitor 110. Controlling the boost converter104 based on the input sensors 118 and/or bus sensors 120 reduces oreliminates the effects of the inductance 100 on the welding output. Insome embodiments, the process control circuitry 102 is configured tocontrol the boost and buck converters 104, 106 to reduce the voltageripple on the internal 108 bus at least while the buck converter 106 isconverting the bus power to a welding output suitable for a controlledwaveform welding process (e.g., pulsed welding, short circuit welding).

The process control circuitry 102 may be configured to reduce thevoltage ripple by adjusting the timing of the control signals for theduty cycle of switches within the boost and buck converters 104, 106. Byadjusting the timing of the control signals, the process controlcircuitry 102 may be configured to generally align pulses (e.g., phases)of the welding output voltage and current with the pulses of the inputcurrent of the input power. The process control circuitry 102 may adjustthe relative timing (e.g., phase shift, advance in time, delay in time)signal pulses from the boost converter 104 and/or buck converter 106 toreduce the voltage ripple. Reducing the voltage ripple on the internalbus 108 may enable the bus capacitor 110 to be smaller, lighter, cooler,more efficient, cheaper, or combinations thereof. The process controlcircuitry 102 may be configured to tune the voltage ripple to a minimumvalue for any inductance 100 of the power cables 24. In this way, theinductance 100 may change during operation of the welding system orbetween welding operations without affecting the voltage ripple on theinternal bus 108 and/or welding output from the buck converter 106.

The input power is received from the welding power source along thepower cable 24 coupled to the input terminals 40. In some embodiments,the input terminals 40 have the first input connection 112 and thesecond input connection 114 with respective defined polarities. Asdiscussed above, the first and second terminals 26, 28 have a positiveand negative polarity, thus the input power is polarized. In someembodiments, sensing circuitry 116 is configured to detect the polarityof the polarized input power supplied to the first and second inputconnections 112, 114 using the input sensors 118. The sensing circuitry116 may be configured to detect a mismatch between the polarities of thefirst and second terminals 26, 28 and defined polarities of the firstand second input connections 112, 114. The process control circuitry 102coupled to the sensing circuitry 116 may be configured to provide thepolarized input power to the power conversion circuitry 58 only if thedetected input power polarity corresponds to the defined polarities ofthe first and second input connections 112, 114. The advanced processwire feeder 20 may be configured to supply a polarized welding outputfor a particular welding application. Switching the polarity of thefirst and second terminals 26, 28 so that the terminals 26, 28 do notcorrespond to the first and second input connections 112, 114 may switchthe polarity of the power cable 62 and work cable 64 from DCEN to DCEP,or from DCEP to DCEN.

In some embodiments, the advanced process wire feeder 20 is configuredto notify the operator of the polarity and/or switch the polarity of theinput power automatically. For example, the process operator interface66 and/or control operator interface 68 may be configured to provide anoperator-perceptible notification if the polarity of the polarized inputpower does not correspond to the defined polarities of the first andsecond input connections 112, 114. The communications circuitry may beconfigured to send and receive command and/or feedback signals over thepower cable to the welding power source. The communications circuitrysends a signal indicative of a mismatch between the polarities of theinput connections so that the welding power source may provide anoperator-perceptible notification of the polarity and/or reverse thepolarity of the input power. In some embodiments, polarity reversingcircuitry 36 (FIG. 1) of the welding power source reverses the polarityof the polarized input power based upon the signal such that thepolarity of the polarized input power corresponds to the definedpolarities of the first and second input connections 112, 114.

The sensing circuitry 116 is also configured to measure the currentand/or voltage of the internal bus 108 with bus sensors 120 and tomeasure the current and/or voltage of the welding output with weldingoutput sensors 122. The process control circuitry 102 monitors the inputsensors 118, bus sensors 120, and welding output sensors 122 through thesensing circuitry 116. Upon detection of a change of the polarized inputpower and/or the welding output to a value outside of a threshold range,the process control circuitry 102 may open relay circuitry 124 tointerrupt provision of the polarized input power to the operationalcomponents of the welding wire feeder 20. The operational components mayinclude, but are not limited to, the power conversion circuitry 58, thewelding wire feed drive 90, or the wire feed control circuitry, or anycombination thereof. The threshold range has a maximum threshold value(e.g., approximately 80V, 100V, 120V, or more) and a minimum thresholdvalue (e.g., approximately 20V, 25V, or 30V). Operating the powerconversion circuitry when the polarized input power and/or the weldingoutput are within the threshold range may increase the stability orconsistency of the conversion. For example, a short circuit downstreamof the relay circuitry 124 may cause a voltage decline across theinternal bus 108 and/or voltage decline of the welding output. Openingthe relay circuitry 124 may protect at least the relay circuitry 124from excess input power due to the short circuit downstream. The relaycircuitry 124 may include circuit elements such as a latching relay,non-latching relay, solid state switches, and so forth. The relaycircuitry 124 is configured to close to provide input power and to opento interrupt input power to the power conversion circuitry 58. In someembodiments, power storage circuitry may provide power to open the relaycircuitry 124 and interrupt input power. The power storage circuitry mayinclude an auxiliary power source 126 and/or the bus capacitor 110 onthe internal bus 108.

Presently contemplated embodiments of the relay circuitry 124 include apower relay 128 and bypass circuitry 130 coupled in parallel at firstand second relay junctions 132, 134. The power relay 128 may be alatching relay or a non-latching relay configured to carry high amperageDC along a first current path 129 when closed. A latching relay may besmaller and lighter than a non-latching relay with the same currentcapacity. In some embodiments, the power relay 128 may be the Relay Type753 manufactured by Gruner of Wehingen, Germany. The bypass circuitry130 may include, but is not limited to, a drive circuit, a voltageclamping device (e.g., metal oxide resistor), and one or more switchesresponsive to drive signals from the drive circuit. The one or moreswitches are configured to carry current along a second current path 131when closed. The voltage clamping device may be configured to clamp thevoltage across the first and second relay junctions 132, 134 in responseto a voltage spike (e.g., rapid increase or decrease) across the relaycircuitry 124. The voltage spike may cause a large current to otherwiseflow along the first and/or second current path 129, 131. The voltageclamping device may be configured to dissipate some of the energy storedin the inductance 100 of the power cables 24. In some embodiments, thebypass circuitry 130 may include at least a pair of switches to protectthe drive circuit if the polarities of the first and second terminals26, 28 do not correspond to the respective defined polarities of thecoupled first and second terminals 112, 114. The bypass circuitry 130may also include multiple solid state switches (e.g., transistors)coupled in parallel to the power relay 128 to provide a desired currentcarrying capacity, such as the high amperage DC input power. The drivecircuit may be the process control circuitry 102 or a separate circuitcontrolled by the process control circuitry 102.

The process control circuitry 102 is configured to apply signals to thepower relay 128 to open and close the power relay 128, and to applysignals to the bypass circuitry 130 to open and close the bypasscircuitry 130 in coordination with opening and closing the power relay128. In some embodiments, the signals to open and close the power relay128 and to open and close the bypass circuitry 130 are appliedsubstantially simultaneously. The bypass circuitry 130 may be configuredto carry a fraction of the input power along the second current path 131to the power conversion circuitry 58 for a short time to reduce theremainder of the input power carried along the first current path 129through the power relay 128 for that short time. When closed, theswitches of the bypass circuitry 130 are configured to reduce thecurrent across the power relay 128 to enable the power relay 128 to openor close without arcing and/or using magnetic blowouts. After theprocess control circuitry 102 signals the power relay 128 to open orclose, the process control circuitry 102 signals the switches of thebypass circuitry 130 to open to interrupt the fraction of the inputpower along the second current path 131. The switches of the bypasscircuitry 130 may be configured to carry the input power along thesecond current path 131 for the short time while the power relay 128 isopened or closed.

The power relay 128 is closed to provide input power to the powerconversion circuitry 58 during welding. In some embodiments, the processcontrol circuitry 102 coupled to the sensing circuitry 116 is configuredto monitor the voltage of the input power and the voltage across theinternal bus 108. The control circuitry 102 is configured to open thepower relay 128 based at least in part on a decline of either the inputvoltage or the voltage across the internal bus 108, which may indicate ashort circuit downstream of the relay circuitry 124. The process controlcircuitry 102 may actuate the power relay 130 with power stored in apower storage circuit, such as the auxiliary power supply 126 or the buscapacitor 110. For example, the process control circuitry 102 maydischarge the power storage circuit to power a coil to open or close thepower relay 128

In some embodiments, a power storage circuit may be charged before thewelding power source provides input power suitable for conversion towelding output. The power storage circuit (e.g., bus capacitor 110) onthe internal bus 108, may be charged by the received input current at aninitial level. In some embodiments, the process control circuitry 102transmits a precharge signal to the welding power source to reduce theinput current of the input power to the initial level. The sensingcircuitry 116 may sense the charge of the power storage circuit with thebus sensors 120. In some embodiments, the process control circuitry 102may initiate a signal to the welding power source to increase the inputcurrent to a greater level based upon a comparison between the inputpower voltage and the voltage across the internal bus 108. In someembodiments, the process control signal receives the input current atthe greater level after the first current path 129 is closed and thesecond current path 131 is opened. Receiving input current at an initiallevel first, and then receiving input current at a greater level enablesa staged initialization of the advanced process wire feeder 20 to reducethe inrush current and input power drawn by the process controlcircuitry 102 and/or the power conversion circuitry 58. For example, theprocess control circuitry 102 may initiate the signal to the weldingpower source when the bus voltage is approximately 50%, 75%, or 100% ofthe input power voltage. In some embodiments, the signal is sent to thewelding power source via the communications circuitry 70 and power cable24.

The bus capacitor 110 between the boost converter 104 and the buckconverter 106 may perform several functions within the advanced processwire feeder 20. The bus capacitor 110 may store power to open or closethe relay circuitry 124 to interrupt the input power flow to theoperational components (e.g., power conversion circuitry 58, wire feeddrive 90, wire feed control circuitry 136). The process controlcircuitry 102 may open or close the relay circuitry 124 based on thevoltage of the bus capacitor 110 and/or the input connections 112, 114.The process control circuitry 102 may also send the signal to thewelding power source based at least in part on the sensed voltage of thebus capacitor 110 and/or input connections 112, 114.

In some embodiments, the bypass circuitry 130 is configured to preventthe power relay 128 from closing if there is a short circuit downstreamof the relay circuitry 124. The process control circuitry 102 may testthe advanced process feeder 20 by closing the second current path 131 todetermine if the voltage of the internal bus 108 may increase. In thecase of a short circuit downstream of the relay circuitry 124, thevoltage of the internal bus 108 would not increase. When the processcontrol circuitry 102 determines that the voltage of the internal bus108 may increase, the process control circuitry 102 may close the powerrelay 128 to enable input power to flow to the power conversioncircuitry 58. Testing the advanced process wire feeder 20 for a shortcircuit downstream of the relay circuitry 124 enables the power relay128 to remain open in the event of a short circuit.

The wire feed assembly 60 is controlled by wire feed control circuitry136 coupled to the wire feed drive 90. The wire feed control circuitry136 may be coupled to the process operator interface 66, the controloperator interface 68, and the process control circuitry 102. The wirefeed control circuitry 136 controls the wire feed drive 90 to supply thewelding wire 54 to the weld cable 62 based at least in part onparameters received via the process operator interface 66 and controloperator interface 68. As discussed above, the process operatorinterface 66 may be configured to receive inputs for gas parameters. Thevalve assembly 72 coupled to the gas line 74 is configured to becontrolled by the process control circuitry 102 and/or the wire feedcontrol circuitry 136.

FIG. 6 illustrates a schematic diagram of an embodiment of the bypasscircuitry 130 of FIG. 5 along line 6-6. As described above, the bypasscircuitry 130 is coupled in parallel with the power relay 128 at thefirst and second relay junctions 132, 134. The bypass circuitry 130includes one or more switches 138, such as metal-oxide-semiconductorfield-effect transistors (MOSFETs), coupled in parallel to the powerrelay 128. In some embodiments, the solid state switches may be arrangedin an anti-series parallel configuration. The power relay 128 and thebypass circuitry 130 are controlled by the process control circuitry toopen and close at substantially the same time to reduce arcing acrossthe power relay 128. Closing the power relay 128 enables current to flowalong the first current path 129 and closing the switches 138 enablescurrent to flow along the second current path 131. The second currentpath 131 may include a number of branches 140, 142, 144, and 146 betweenparallel switches. Changing the number of branches affects the currentcarrying capacity along the second current path 131, thus affecting thecurrent along the first path 129 when the power relay 128 is actuated.Reducing the current along the first path 129 when actuating the powerrelay 128 reduces arcing between contacts of the power relay. Theprocess control circuitry is configured to control the one or moreswitches 138 through a gate 148 or other control switch to open andclose the one or more switches 138 simultaneously or sequentially. Theone or more switches 138 are configured to be open unless controlled bythe process control circuitry to close.

Upon receiving control signals from the process control circuitry, theone or more switches 138 are configured to close, opening the secondcurrent path 131. While the one or more switches 138 are closed, theprocess control circuitry controls the power relay 128 to actuate openor closed with a reduced current along the first current path 129 due tothe current along the second current path 131. After the power relay 128is actuated open or closed, the process control circuitry opens the oneor more switches 138 to open the second current path 131. The controlsignals from controlling the one or more switches 138 and the powerrelay 128 may be pulses that open and close the first and second currentpaths 129, 131 substantially simultaneously. That is, the power relay128 may open and close the first and second current paths 129, 131 inapproximately 5 to 50 milliseconds, 10 to 40 milliseconds, orapproximately 20 to 30 milliseconds.

The bypass circuitry 130 includes a voltage clamping device 150 (e.g.,(e.g., metal oxide resistor, varistor) to protect the one or moreswitches 138 and power relay 128 from over-voltages. Upon opening thepower relay 128, the voltage between the first and second relayjunctions 132, 134 may increase as the bus capacitor, power cables,and/or auxiliary power source, or other circuitry releases storedcharge. The voltage clamping device 150 is configured to have greaterelectrical resistance at higher voltages than at lower voltages. Thevoltage clamping device 150 carries more current along the third currentpath 152 as the voltage between the first and second relay junctions132, 134 increases to maintain the current along the first and secondcurrent paths 129, 131 below threshold levels.

The advanced process wire feeder of FIG. 5 may be utilized according tomultiple methods as illustrated in FIGS. 7-10. Some embodiments of theadvanced process wire feeder may be utilized with all of the illustratedembodiments of FIGS. 7-10. Other embodiments of the advanced processwire feeder may be utilized with only some of the illustratedembodiments of FIGS. 7-10. FIG. 7 illustrates a method 154 of convertinginput power to controlled waveform welding output within an advancedprocess wire feeder. The first step 156 of the method is to receiveinput power from the welding power source. In some embodiments, theinput power may be a polarized DC input power of approximately 80V. Theinput power may not be suitable for a controlled waveform weldingprocess if it was directly supplied to the welding torch. In step 158,an operator may open the enclosure of the advanced process wire feeder.The operator may open the enclosure to install or change the weldingwire spool or to adjust parameters relating to the welding wire and gassupply. At step 160, the process operator interface within the enclosurereceives the wire and/or gas parameter before the enclosure is closed atstep 162. At step 164, the process control circuitry determines theprocess parameters. The process parameters include a controlled waveformoutput, the amperage, the feed rate of the welding wire, and so forth.The process parameters may be determined based on the parametersreceived through the process operator interface. In some embodiments,the control circuitry automatically determines the process parametersfor a controlled waveform welding output based on code and/orinstructions stored in memory without direct selection of the processtype by the operator. The advanced process wire feeder may communicatewith the welding power source at step 166 to adjust the input powerbased at least in part on the received process and/or wire parameters.In some embodiments, step 166 may occur at any time during operation ofthe advanced process wire feeder. At block 168, the advanced processwire feeder converts the input power to welding output. The weldingoutput may be a controlled waveform welding output suitable for a shortcircuit or pulsed welding process. The welding output converted by thepower conversion circuitry within the advanced process wire feeder isnot attenuated by inductance of the power cable coupled to the weldingpower source. The advanced process wire feeder receives shielding gas atstep 170. The shielding gas may be supplied through the welding powersource or a separate gas supply. At step 172, the advanced process wirefeeder provides the wire and gas to the welding torch based at least inpart on the input received at steps 160 and 164. At step 174, thewelding output is provided to the welding torch, based at least in parton the input received at step 164. The welding output may be suitablefor a controlled waveform welding process because of the relativelyshort distance and low inductance between the power conversion circuitryand the welding torch.

FIG. 8 illustrates a method 176 of sensing the polarity of the inputpower received by the advanced process wire feeder. At step 178, theadvanced process wire feeder receives polarized input power from thewelding power source. The polarized input power is supplied along firstand second terminals of the power cable. The input power is received attwo input connections, each with a defined polarity. At block 180,sensing circuitry detects the polarity and voltage of the polarizedinput power with input sensors at the first and second inputconnections. In some embodiments, at block 182, the received input powermay charge power storage circuitry, such as an auxiliary power sourceand/or a bus capacitor.

Upon detecting the polarity of the input power at step 180, the controlcircuitry verifies at node 184 whether the first and second terminalscorrespond to the defined polarities of the input connections. If thereis a mismatch between the polarities, process control circuitry withinthe advanced process wire feeder may notify the operator with anoperator-perceptible notification of the mismatched polarity through theprocess operator interface, the control operator interface, and/or thewelding power source. Alternatively, at block 188 the process controlcircuitry may communicate with the welding power source to direct thewelding power source to change the polarity of the input power as shownat block 190. If the polarity of the input power matches the polarity ofthe defined polarity connections, then the process control circuitrydetermines at node 192 whether the input power and input voltage issubstantially stable. If the input voltage is stable, the input power issupplied to the power conversion circuitry. The process controlcircuitry may periodically sense and determine whether the input voltageis stable at node 192 during the welding process. If the input voltageis not stable, the process control circuitry may interrupt the polarizedinput power supply to the power conversion circuitry. The processcontrol circuitry may interrupt the polarized input power by opening apower relay upstream of the power conversion circuitry and/orcommunicating with the welding power source to cease supplying theadvanced process wire feeder with input power. If the input power isinterrupted, the method 176 may be repeated from step 178 when polarizedinput power is received.

If the input voltage is stable, the input power is supplied to the powerconversion circuitry to convert the polarized input power to weldingoutput at block 196. The welding output may be a controlled waveformwelding output suitable for a short circuit or pulsed welding process.Additionally, the welding output may be suitable for a FCAW process orGMAW welding process. The welding output converted by the powerconversion circuitry within the advanced process wire feeder 20 is notattenuated by inductance of the power cable coupled to the welding powersource. The advanced process wire feeder receives shielding gas at step170. The shielding gas may be supplied through the welding power sourceor a separate gas supply. At step 172, the advanced process wire feederprovides the wire and gas to the welding torch. At step 174, the weldingoutput is provided to the welding torch. The welding output provided maybe suitable for a controlled waveform welding process because of therelatively short distance and low inductance between the powerconversion circuitry and the welding torch.

FIG. 9A illustrates a first part of a method 198 of precharging circuitelements of the advanced process wire feeder and using bypass circuitryin parallel with the power relay. The advanced process wire feeder sendsa precharge signal to the welding power source at step 199 when theadvanced process wire feeder is electrically coupled to the weldingpower source. The precharge signal directs the welding power source tolimit the current of the precharge input power to an initial level. Atstep 200, the advanced process wire feeder receives the input power atthe initial level. At step 201, the process control circuitry sends acontrol signal to the bypass circuit to close the second current path totransmit the input power at the initial level to the power storagecircuitry (e.g., bus capacitor on the internal bus). The input power atthe initial level charges power storage circuitry (e.g., bus capacitor)at step 202. The sensing circuitry detects the voltages of the inputpower and bus power at step 204. The voltage of the bus power is ameasure of the power stored in the bus capacitor. At node 206, theprocess control circuitry compares the voltages of the input power andthe bus power. In some embodiments at node 206, the process controlcircuitry tests the relay circuitry as described above with FIG. 5 todetermine the presence of a short circuit downstream of the relaycircuitry. If a short circuit is present downstream (e.g., the voltageis below a threshold), the process control circuitry may not close thepower relay so that the input power does not pass through the shortcircuit. The process control circuitry may open the bypass circuit atblock 207 in case of a short downstream. After the bypass circuit opens,the voltage clamping device clamps the voltage at block 209 to at leastpartially protect the relay circuitry. The process control circuitry maysend a signal at block 211 to the welding power source, the processoperator interface, and/or the control operator interface. In someembodiments, the signal may control the welding power source to haltproduction of the input power. In other embodiments, the signal controlsthe operator interface to indicate a fault (e.g., short circuit) atblock 213 to the operator. If the voltage of the bus power is above athreshold (e.g., the power storage circuitry is charged) and no shortcircuit is present, the process control circuitry sends a control signalto the power relay to close the first current path at step 208.

After the power relay is closed, at step 210 the process controlcircuitry sends a control signal to the bypass circuit to open thesecond current path. In some embodiments, the process control circuitrysends a signal to the welding power source at block 212. The signaldirects the welding power source to increase the current of the inputpower to a greater level. In other embodiments, the welding power sourceis configured to increase the current to the greater level after adefined period of time after step 210. In some embodiments, the processcontrol circuitry of the advanced process wire feeder may perform thesteps 208 and 210 substantially simultaneously, or within less thanapproximately 50 milliseconds, less than approximately 30 milliseconds,or less than approximately 15 milliseconds. The advanced process wirefeeder receives the input power at the greater level at block 214. Theinput power at the greater level is suitable for conversion to weldingoutput at block 216 for a desired welding process.

The power conversion circuitry of the advanced process wire feederconverts the input power at the greater level to welding output at step216. The welding output may be a controlled waveform welding outputsuitable for a short circuit or pulsed welding process. Additionally,the welding output may be suitable for a FCAW process or GMAW weldingprocess. The welding output converted by the power conversion circuitrywithin the advanced process wire feeder is not attenuated by inductanceof the power cable coupled to the welding power source. FIG. 9Billustrates a second part of the method 198 that may be configuredduring and after block 216. During a welding process, at node 218,control circuitry monitors voltages of input power and bus power tocontrol the relay circuitry. In some embodiments, the sensing circuitrymay also detect the polarity of the input power as described above withmethod 176 in FIG. 8 to notify the operator of a polarity mismatch orreverse the polarity at the welding power source.

If the sensing circuitry detects a declining voltage across the internalbus and/or a declining voltage of the input power, the process controlcircuitry actuates the relay circuitry in steps 220, 224, and 226 tointerrupt the input power to the power conversion circuitry. The processcontrol circuitry sends a control signal to the bypass circuit at step220 to close the second current path. At the same time or shortly afterstep 220, the process control circuitry sends a control signal to thepower relay at step 224 to open the first current path. The processcontrol circuitry may discharge at least some of the power storagecircuit to drive the power relay open. For example, the power storagecircuit may store power to drive a magnetic coil to open power relayupon receipt of a control signal from the process control circuitry.After the power relay is open, at step 226 the process control circuitrysends a control signal to the bypass circuit to open the second currentpath. In some embodiments, the process control circuitry of the advancedprocess wire feeder may perform the steps 220, 224, and 226substantially simultaneously, or within less than approximately 50milliseconds, less than approximately 30 milliseconds, or less thanapproximately 15 milliseconds. After the first and second current pathsare open, the voltage across the relay circuitry may increase due topower stored within the power cables and/or power storage circuit. Avoltage clamping device of the relay circuitry clamps the voltage atblock 228 to reduce the effects of the stored energy on the power relayor bypass circuit. Throughout the method 198, such as if the sensingcircuitry detects stable voltages of the input power and bus power, theadvanced process wire feeder may communicate with the welding powersource at step 230. The advanced process wire feeder may direct thewelding power source to adjust the input power (e.g., cease supplyingthe input power).

The advanced process wire feeder receives shielding gas at step 170. Theshielding gas may be supplied through the welding power source or aseparate gas supply. At step 172, the advanced process wire feederprovides the wire and gas to the welding torch. At step 174, the weldingoutput is provided to the welding torch. The welding output provided maybe suitable for a controlled waveform welding process because of therelatively short distance and low inductance between the powerconversion circuitry and the welding torch.

FIG. 10 illustrates a method 232 of controlling the current of the inputpower to reduce voltage ripple on the internal bus. The first step 234of the method 232 is to receive input power from the welding powersource. In some embodiments, the input power may be a polarized DC inputpower of approximately 80V. Throughout the method 232, the advancedprocess wire feeder may communicate with the welding power source asshown at step 236. The boost converter of the power conversion circuitryreceives the input power and converts the input power to bus power atstep 238. The bus power is transmitted from the boost converter to thebuck converter along the internal bus. Sensing circuitry detects thecurrent and voltage of the bus power at step 240. At step 242, the buckconverter converts the bus power from the internal bus to weldingoutput. The welding output may be a controlled waveform welding outputsuitable for a short circuit or pulsed welding process. Additionally,the welding output may be suitable for a FCAW process or GMAW weldingprocess. The sensing circuitry also detects the current and voltage ofthe welding output at step 244.

The process control circuitry receives the detected currents andprocesses the detected measurements to adjust the power conversioncircuitry. In some embodiments, the process control circuitry isconfigured to determine the desired current of bus power to reduce thevoltage ripple across the internal bus. The process control circuitrymay determine the desired current of bus power by determining theproduct of the welding output current and voltage, determining the sumof the product and a conversion loss, and dividing the sum by the busvoltage. The process control circuitry may adjust the command signals tothe boost and buck converters at step 248 based on the detected currentand voltage measurements from steps 240 and 244. In some embodiments,the process control circuitry adjusts the command signals to the powerconversion circuitry to substantially match in time the bus powerentering the internal bus with the bus power entering the buckconverter. This reduces the voltage ripple across the internal bus. Theprocess control circuitry is configured to adjust the current of the buspower based at least in part on the welding output. In some embodiments,the process control circuitry is configured to adjust the duty cycle ofswitches within the boost converter to advance or delay in time (e.g.,phase shift) the conversion of input power to bus power. The processcontrol circuitry is also configured to adjust the duty cycle ofswitches within the buck converter to advance or delay in time (e.g.,phase shift) the conversion of bus power to welding output. In someembodiments, the process control circuitry is configured to dynamicallyadjust the boost converter and buck converter based on feedback to tunethe voltage ripple to a minimum value. The process control circuitry isconfigured to tune the voltage ripple to the minimum value for anyinductance of the power cables.

The advanced process wire feeder receives shielding gas at step 170. Theshielding gas may be supplied through the welding power source or aseparate gas supply. At step 172, the advanced process wire feederprovides the wire and gas to the welding torch. At step 174, the weldingoutput is provided to the welding torch. The welding output provided maybe suitable for a controlled waveform welding process because of therelatively short distance and low inductance between the powerconversion circuitry and the welding torch.

FIG. 11 is a chart 249 illustrating an embodiment of the bus voltage,input current, and welding output parameters versus time of the advancedprocess wire feeder without adjusting the power conversion circuitry.The chart 249 illustrates a series of input current pulses on theinternal bus supplied by the boost converter, and the welding outputdrawn by the buck converter from the internal bus suitable for acontrolled waveform welding process. The signal 250 is the voltageripple as measured on the internal bus. The signal 252 is the outputcurrent of the welding output drawn by the buck converter, and thesignal 254 is the output voltage of the welding output drawn by the buckconverter. Signal 256 is the current of the converted bus power suppliedby the boost converter from the input power. Each of the signalsillustrated has a regular period, however, the output timing (e.g.,phase) of the output current and voltages 252, 254 precedes the inputtiming (e.g., phase) of the bus current 256. That is, the timing of apeak 260 of the bus current 256 is offset (e.g., delayed) from thetiming of peaks 258 of the welding output current 252 and welding outputvoltage 254. The relative time difference between the output peak 258and the input peak 260 of the chart 249 causes the voltage ripple tohave a large peak-to-peak amplitude 262.

FIG. 12 is a chart 264 illustrating an embodiment of the bus voltage,input current, and welding output parameters versus time of the advancedprocess wire feeder for which the power conversion circuitry is adjustedto reduce the voltage ripple. In this embodiment, the peak-to-peakamplitude 262 of the voltage ripple 250 is substantially less than inchart 249 of FIG. 11. The process control circuitry controls the dutycycles of switches within the boost converter and/or the buck converterto reduce the voltage ripple 250. For example, the process controlcircuitry adjusts the timing of the output peak 258 of the outputcurrent and voltage, adjusts the timing of the input peak 260 of the buscurrent, or combinations thereof. FIG. 12 illustrate an embodiment inwhich the process control circuitry delays the timing of the output peak258 to more closely coincide with the timing of the input peak 260,thereby reducing the peak-to-peak amplitude 262 of the voltage ripple250. In some embodiments, the voltage ripple 250 is reduced when theinput current 256 and input voltage signals are aligned in time with theoutput current 252 and the output voltage 254. The product of the inputcurrent 256 and the input voltage signals may be approximately equal toa sum of a conversion loss (e.g., from the boost converter and the buckconverter) and the product of the output current 252 and the outputvoltage 254 signals. In some embodiments, the process control circuitrycontrols the conversion by the boost and buck converters to refine theshape of the pulsed waveforms to further reduce the voltage ripple. Forexample, the bus current 256 of the embodiment of chart 264 increasesand decreases more rapidly than the embodiment of chart 249.Additionally, the process control circuitry may control the bus current256 supplied by the boost converter to closely match the current of thewelding output 252 drawn by the buck converter as illustrated in chart264.

FIG. 13 illustrates an exemplary current management system as may beused in either a pendant coupled to a welding power source or in aremote wire feeder, of the types described above. The current managementsystem, designated generally by reference numeral 268 is designed to becoupled to a welding power source 12 via a power cable 24. Because thewelding power source 12 may often be live (i.e., powered and providingoutput power to the cables 24), the current management system 268 mayserve multiple functions, such as to limit inrush current to energystorage devices within the remote component, and/or to delay applicationof current to the energy storage devices to avoid arcing at the terminalconnections when the component is coupled to the live welding powersource. In the illustrated embodiment, the current management system 268includes at least one energy storage device 270 coupled to a local powersupply 272 within the component. The local power supply may be used toprovide power for various accessories 274, such as user interfaces,displays, and so forth. The energy storage device 270 may include one ormore types of devices, such as capacitors, batteries, combinations ofthese, or any other suitable energy storage devices. A charge/dischargecontrol circuit 276 is also provided for regulating application ofcurrent to the energy storage device 270 and for regulating the flow ofpower from the energy storage device. These devices may be coupled in abussed circuit arrangement as illustrated, with welding power beingprovided to a welding torch in parallel with this circuitry. Moreover,current and voltage sensors may be incorporated into the circuitry forregulating operation of certain of the components, particularly duringinitial connection of the pendant or wire feeder to a power source andalso during operation.

As described more fully below with reference to FIGS. 14 and 15, thecurrent management system 268 serves to limit current into the energystorage device by operation of the charge/discharge control circuit. Inparticular, during use, the circuitry may ensure that the welding poweroutput does not “starve” the local power supply 272, such as during arcstarting (e.g., lift-arc starting in TIG operations). Moreover, thecurrent draw can be made low enough via the circuitry to prevent arcingwhen the pendant or wire feeder is connected to a live welding powersource. So further, energy from the energy storage device may be used tomaintain power to the accessory 274 during loss of open circuit voltage(i.e., “ride-through”).

FIG. 14 illustrates an exemplary charge/discharge control circuit 276such as may be suitable for a limiting inrush current to a remotecomponent, such as a welding pendant. The energy storage device 270 ishere illustrated as a series of capacitors. A charge path 278 is definedthrough a resistor 280 and a switch 282. In the illustrated embodiment,the resistor 280 is a relatively low resistance, such as 100 Ohms,although any suitable resistance could be used, and the switch 282includes a MOSFET, although any suitable switch may be used. Theresistor 280 will initially limit the flow of current to the capacitorsupon connection of the component to a live power source. Current to thecapacitors is limited by resistor 280 and by switch 282 under control ofa Zener diode 286 (or another device, such as a circuit that mimicsaspects of a Zener diode and an error amplifier in combination). Thiscurrent can be made low enough by selection of the individual electricalcomponents to prevent arcing when the pendant is connected to a weldingpower source open current voltage. Diodes 284 are provided forprotection purposes. A current-limiting effect is provided by diode 286(or other device as mentioned above) and a resistor 288 that acttogether to limit current by modulating the conductive state of switch282. In a current circuit design, for example, the current flow is notallowed to exceed approximately 0.5 Amps. That is, switch 282 allows forcharging of the capacitors, and this switch is maintained in aconductive state, but is throttled back to a limited current byinteraction of components 286 and 288.

Moreover, an additional diode 290 (which again may be a circuit thatmimics aspects of a diode in combination with an error amplifier) andadditional resistors 292 are provided that act together to limitvoltage. That is, these components as coupled in the illustrated diagramact to reduce the bias of switch 282 to effectively limit the voltage ofthe device. Consequently, relatively low voltage capacitors may beutilized.

In operation, the circuitry effectively limits the inrush of currentwhen the component is initially coupled to a live power source, in thiscase any spark being limited to approximately 0.5 Amps. The storagedevices, in this case a series of capacitors, are then allowed tocharge. Thereafter, “ride-through” capabilities are provided by thecapacitors which feed the local power supply 272 during a loss ofwelding power through a diode. It should be noted that the circuitryillustrated in FIG. 14, and indeed that of FIG. 13 and FIG. 15 describedbelow are intended to be in addition to any other circuitry provided inthe remote component, whether a pendant or wire feeder. That is, thosecomponents may nevertheless include various sensing, processing,control, wire feed, and other circuitry of the types described above.

FIG. 15 illustrates another exemplary circuit that may be used forcurrent and/or power management in a remote device, in this case isparticularly well-suited to a wire feeder of the type described above.The circuitry also includes a local power supply 272, as well as storagedevices 270, in this case multiple capacitors. The application ofcurrent into the capacitors is delayed until a further capacitor 296 ischarged through a resistor 298 to a gate threshold of a solid stateswitch 294. This delay, then, prevents or reduces the likelihood ofarcing when the component is initially coupled to a live welding powersource. Moreover, a voltage across the capacitors is effectively limitedby interaction of a second solid state switch 300 and a diode 302. Thatis, when the diode 302 changes to a conductive state, the gate of switch300 is powered, placing switch 294 in a non-conductive state. Currentout of the capacitors passes through the internal diode of the packageof switch 294.

Various enhancements to the circuitry of FIG. 15 may be easilyenvisaged, for example, a comparator could be provided between switch294 and capacitor 296 to provide a “snap-on” operation in which thelinear mode of switch 294 is effectively avoided. The circuitry thusprovides a bi-directional, low impedance energy storage arrangement thateffectively reduces or avoids arcing upon initial connection, whileproviding the desired local power supply capabilities and ride-throughcapabilities during operation.

FIG. 16 is an embodiment of the welding system 10 with a power supply 12coupled to the device 310 via power cables 24. As discussed above, thedevice 310 may include, but is not limited to, the advanced process wirefeeder 20 discussed above and illustrated in FIGS. 1-5. The power cables24 couple the first and second terminals 26, 28 to the input terminals40 of the device 310. For example, a first power cable 312 couples thefirst terminal 26 to the first connection 112, and a second power cable314 couples the second terminal 28 to the second connection 114. Each ofa first set 316, a second set 318, and a third set of power cables 24may have different inductance values based at least in part onproperties of the respective power cables 24. Properties that may affectthe inductance of a power cable 24 may include, but is not limited to,length, material, disposition (e.g., coiled, straight) relative to thewelding system 10, disposition relative to conductive materials,arrangement (e.g., parallel, twisted) relative to other power cables 24,and proximity to inductive sources (e.g., other power cables 24). Forexample, the first set 316 of power cables 24 that are coiled may have agreater inductance than the second set 318 of power cables 24 that areuncoiled. Furthermore, the third set 320 of power cables 24 may have alesser inductance than the first and second sets 316, 318 of powercables 24 due to being uncoiled and having a relatively short length322. As may be appreciated, various embodiments of the power cables 24are not limited to the first, the second, and the third sets 316, 318,and 320 of power cables 24.

The power supply 12 provides power output to the device 310 along theset of the power cables 24. The device 310 and the power supply 12 maycommunicate via wireless connections or wired connections, such as thepower cables 24. For example, the communications circuitry 70 of thedevice 310 may communicate with the communications circuitry 38 of thepower supply 12. The device 310 may communicate power demands of a load324 to the power supply 12, and the control circuitry 32 of the powersupply 12 controls the power conversion circuitry 30 to change the poweroutput to satisfy the requested power demand. For example, the device310 may communicate changes to settings of the voltage (e.g., weldvoltage) and/or the current to be supplied by the power supply 12 duringoperation of the device 310. During operation of the device 310 (e.g.,during weld formation), the device 310 increases the power outputdemanded from the power supply 12 by the load 324. The load 324 mayinclude, but is not limited to, power conversion circuitry (e.g., boostconverter, bus capacitor, buck converter), motor, pump, light, powertool, or any combination thereof. For example, upon user actuation of atrigger of a welding torch coupled to the device 310, the device 310increases the power output demanded from the power supply 12, therebyincreasing the voltage and/or the current along the power cables 24.Upon release of the trigger, the device 310 decreases the power outputdemanded from the power supply 12, thereby decreasing the voltage and/orthe current along the power cables 24. In some embodiments, the device310 and the power supply 12 may communicate during idle operation of thewelding system 10 and/or while the device 310 is providing power output(e.g., welding output) to the load 324. For example, the device 310 maycommunicate with the power supply 12 during weld formation by a torchcoupled to the device 310.

During idle operation of the welding system 10, such as at start up ofthe welding system 10 or between welding operations, the device 310 maydetermine the inductance of the power cables. In some embodiments, thecommunications circuitry 70 of the device 310 may be paired (e.g.,synchronized) with the communications circuitry 38 of the power supply12. When paired, the communications circuitry 70 and/or thecommunications circuitry 38 may verify that the power cables 24 couplethe device 310 and the power supply 12. To verify the maintainedcoupling via the power cables, the device 310 may periodically changethe current demanded from the power supply 12, and the power supply 12may respond in a prescribed manner. For example, during idle operation,the device 310 may briefly change the current demand by a prescribedamount (e.g., 1, 2, 3, 4, 5, 6, 7, 8 9, 10 Amperes) at intervals ofapproximately 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or more seconds. In anembodiment where the device 310 is an advanced process wire feeder 20,the device may briefly change the current demand by turning on the boostconverter. The current provided by the power supply 12 changes based atleast in part on the changed current demand, and the device 310 verifiesthe maintenance of the connection by monitoring the power input receivedvia the power cables 24 during a verification interval (e.g.,approximately 10 seconds).

The sensing circuitry 116 of the device senses the current and/orvoltage of the power output received by the device 310. As describedherein, the device 310 monitors characteristics of the power outputprovided to the device 310 in response to the changed current demandfrom the device 310, thereby enabling the device 310 to determine theinductance of the power cables 24 carrying the power output from thepower supply 12. For example, a delay for the sensed voltage rise to athreshold voltage after the sensed current demand begins to increasecorresponds to an inductance value. The device 310 compares thedetermined inductance to threshold inductance values stored in a memory.In some embodiments, an operator interface 326 may provide anotification (e.g., display, sound, light) indicating that thedetermined inductance of the power cables 24 is greater than thethreshold inductance. Additionally, or in the alternative, the device310 may disable operation of the device 310 until the determinedinductance is less than the threshold inductance. That is, the device310 may disable operation of the load 324 and/or the device 310 may stoptransmission of power output through the weld cable 62 or the work cable64 coupled to the device 310 when the determined inductance is greaterthan the threshold inductance.

FIG. 17 illustrates a chart of an input voltage (V_(bus)) and inputcurrent (I_(load)) versus time, where V_(bus) and I_(load) are providedover power cables to the device 310 from a power supply 12. While theembodiments discussed herein with FIG. 17 may include the advancedprocess wire feeder 20 as the device 310 where the load 324 is the powerconversion circuitry 58 (e.g., boost converter 104, bus capacitor 110,buck converter 106), the inductance of power cables 24 may be determinedby sensing circuitry 116 of any coupled device 310. During idleoperation of the device 310, the V_(bus) and I_(load) may remainsubstantially constant at V₁ and I₁ respectively. At T₁, the boostconverter of the load increases the current demand from the power supplyfrom I₁ to I₂. The input current I_(load) received from the power supplybegins to increase at T₁, and increases at a ramp rate 350 towards I₂.The inductance of the power cables causes the change in V_(bus) to lagbehind I_(load) for a voltage transient duration 352, as shown by theflat portion of V_(bus) of FIG. 17. After the voltage transient 352,V_(bus) begins to increase, reaching a threshold voltage (V_(threshold))at T₂. The threshold voltage may be stored in a memory of the device310, and may be any value between V₁ and V₂. For example, V_(threshold)may be approximately 5, 10, 15, 20, 25, 30, 40, or 50 percent greaterthan V₁.

The control circuitry of the device 310 may determine the inductance ofthe power cables via monitoring the response of V_(bus) and/or I_(load).That is, the control circuitry may determine the inductance of the powercables via monitoring the time delay between T₂ and T₁ when V_(bus) isapproximately equal to V_(threshold), the ramp rate of I_(load), thetime delay between T₁ and T₃ when I_(load) is approximately equal to I₂,or a relative comparison of the V_(bus) to I_(load), or any combinationthereof. The delay between T₁ and T₂ is based at least in part on theinductance of the power cables that transmit the power output from thepower supply to the device 310. For example, increasing the inductanceof the power cables may increase the delay, and decreasing theinductance of the power cables may decrease the delay. The ramp rate 350of I_(load) may be based at least in part on the inductance of the powercables that transmit the power output from the power supply to thedevice. For example, increasing the inductance of the power cables maydecrease the ramp rate 350, and decreasing the inductance of the powercables may increase the ramp rate 350. Additionally, or in thealternative, the control circuitry may determine the inductance of thepower cables based at least on a measure of the received voltage at atime when the received current is approximately 50% between I₁ and I₂.Furthermore, the delay between T₁ and T₃ may be proportional to theinductance of the power cables.

FIG. 18 is a flow chart of an embodiment of a method 398 for determiningthe inductance of power cables between a power supply and a device ofthe welding system. The device may signal (block 400) the power supplyat a time T₀ that the current demand will change at T₁. Accordingly, thedevice coordinates with the power supply to change (block 402) the poweroutput supplied from the power supply at T₁. Control circuitry of thedevice monitors (block 404) the current and the voltage of the poweroutput received by the device. For example, the sensing circuitry maymeasure (block 406) the voltage delay when the received voltage reachesV_(threshold) (e.g., T₂−T₁). In some embodiments, the sensing circuitrymay measure (block 408) V_(bus) relative to and I_(load). In someembodiments, the sensing circuitry may measure (block 410) a ramp rateof the received current. Additionally, or in the alternative, thesensing circuitry may measure (block 412) the current delay when thereceived current reaches the demand current (e.g., T₃−T₁).

Based at least in part on measurements of the sensing circuitry whilemonitoring (block 404) the received voltage and current, the controlcircuitry determines (block 414) the inductance (L_(cable)) of the powercables. The control circuitry may determine the inductance of the powercables based at least in part on comparison of the measured values ofblocks 406-412 with values stored in a memory. For example, the controlcircuitry may utilize a look up table, an algorithm, or a model storedin a memory to determine the inductance of the power cables. At node416, the sensing circuitry determines whether L_(cable) is greater thana threshold inductance (L_(threshold)). The threshold inductance may bea value input by the user and/or a value stored in a memory. In someembodiments, the threshold inductance is based at least in part on thestorage capacity of the power storage circuitry of the device, or adesired quality of the power output from the device, or any combinationthereof. For example, the device may be configured to reduce oreliminate the effects of the inductance when L_(cable) is less thanL_(threshold). If the L_(cable) is greater than L_(threshold), thedevice may signal (block 418) the operator (e.g., via a display, sound,light) that the determined inductance of the power cables 24 is greaterthan the threshold inductance. In response to the signal from thedevice, the user may change the power cables and/or adjust thearrangement of the power cables to attempt to reduce the inductance.While L_(cable) is greater than L_(threshold), the control circuitrydisables (block 420) the operation of the device.

If L_(cable) is less than L_(threshold), the control circuitry may reset(block 422) a pairing counter, thereby enabling the device to remain inan idle operation mode until the power output (e.g., weld output) isdemanded from the device. The control circuitry waits (block 424) forthe sample interval before repeating method 398 to determine theinductance of the power cables and to verify whether the device remainscoupled to the power supply via the power cables. At node 426, thecontrol circuitry enables operation of the device if it was previouslydisabled at block 420. For example, where the control circuitry disabled(block 420) operation of the device due to the value of L_(cable), thesensing circuitry may enable (block 428) operation of the device in asubsequent iteration of the method 398 after the user has adjusted orreplaced the power cables to reduce L_(cable).

While only certain features of the invention have been illustrated anddescribed herein, many modifications and changes will occur to thoseskilled in the art. It is, therefore, to be understood that the appendedclaims are intended to cover all such modifications and changes as fallwithin the true spirit of the invention.

The invention claimed is:
 1. A welding system comprising: awelding-related device configured to be coupled to a power supply viapower cables, wherein the welding-related device is configured toreceive power from the power supply via the power cables, and thewelding-related device comprises sensing circuitry configured to sense aparameter indicative of a delay between when the power is output fromthe power supply and when the power is received by the welding-relateddevice through the power cables.
 2. The welding system of claim 1,wherein the welding-related device comprises an advanced process wirefeeder.
 3. The welding system of claim 1, wherein the sensing circuitryis configured to sense the parameter indicative of the delay based atleast in part on another delay in a voltage of the received powerchanging to a threshold voltage after a change in a current of thereceived power.
 4. The welding system of claim 1, wherein the sensingcircuitry is configured to sense the parameter indicative of the delaybased at least in part on a ramp rate of a current of the receivedpower.
 5. The welding system of claim 1, further comprising controlcircuitry configured to determine the parameter indicative of the delaybased at least in part on a comparison of a voltage of the receivedpower to a current of the received power after a change in the current.6. The welding system of claim 1, wherein the sensing circuitry isconfigured to sense the parameter indicative of the delay based at leastin part on another delay in a current of the received power changing toa demand current.
 7. The welding system of claim 1, wherein thewelding-related device comprises a plasma cutter.
 8. The welding systemof claim 1, wherein the welding-related device comprises an inductionheater.
 9. The welding system of claim 1, wherein the welding-relateddevice comprises a power generator.
 10. The welding system of claim 1,wherein the welding-related device comprises a welding power source. 11.The welding system of claim 1, wherein the parameter indicative of thedelay comprises an inductance of the power cables.
 12. The weldingsystem of claim 11, wherein the welding-related device is configured toprovide a signal when the inductance is greater than a thresholdinductance.
 13. The welding system of claim 11, wherein thewelding-related device is configured to disable operation of thewelding-related device when the inductance is greater than a thresholdinductance, and the welding-related device is configured to enableoperation of the welding-related device when the inductance is less thanthe threshold inductance.
 14. A welding wire feeder comprising: inputterminals configured to receive power from a power supply through powercables connected to the input terminals; sensing circuitry configured tosense a parameter indicative of a delay between when the power is outputfrom the power supply and when the power is received through the powercables; and control circuitry configured to adjust operation of thewelding wire feeder based at least in part on the parameter indicativeof the delay.
 15. The welding wire feeder of claim 14, wherein thesensing circuitry is configured to sense the parameter indicative of thedelay based at least in part on another delay in a voltage of thereceived power changing to a threshold voltage after a change in acurrent of the received power.
 16. The welding wire feeder of claim 14,wherein the sensing circuitry is configured to sense the parameterindicative of the delay based at least in part on a ramp rate of acurrent of the received power.
 17. The welding wire feeder of claim 14,wherein the control circuitry is configured to determine the parameterindicative of the delay based at least in part on a comparison of avoltage of the received power to a current of the received power after achange in the current.
 18. The welding wire feeder of claim 14, whereinthe sensing circuitry is configured to sense the parameter indicative ofthe delay based at least in part on a delay in a current of the receivedpower changing to a demand current.
 19. The welding wire feeder of claim14, wherein the parameter indicative of the delay comprises aninductance of the power cables.
 20. The welding wire feeder of claim 19,wherein the control circuitry is configured to disable operation of thewelding wire feeder when the inductance is greater than a thresholdinductance, and the control circuitry is configured to enable operationof the welding wire feeder when the inductance is less than thethreshold inductance.